SNVSBU3 March   2021 LP87702

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Serial Bus Timing Parameters
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Descriptions
      1. 7.3.1  Step-Down DC/DC Converters
        1. 7.3.1.1 Overview
        2. 7.3.1.2 Transition Between PWM and PFM Modes
        3. 7.3.1.3 Buck Converter Load Current Measurement
      2. 7.3.2  Boost Converter
      3. 7.3.3  Spread-Spectrum Mode
      4. 7.3.4  Sync Clock Functionality
      5. 7.3.5  Power-Up
      6. 7.3.6  Buck and Boost Control
        1. 7.3.6.1 Enabling and Disabling Converters
        2. 7.3.6.2 Changing Buck Output Voltage
      7. 7.3.7  Enable and Disable Sequences
      8. 7.3.8  Window Watchdog
      9. 7.3.9  Device Reset Scenarios
      10. 7.3.10 Diagnostics and Protection Features
        1. 7.3.10.1 Voltage Monitorings
        2. 7.3.10.2 Interrupts
        3. 7.3.10.3 Power-Good Information to Interrupt, PG0, and PG1 Pins
          1. 7.3.10.3.1 PGx Pin Gated (Unusual) Mode
          2. 7.3.10.3.2 PGx Pin Operation in Continuous Mode
          3. 7.3.10.3.3 Summary of PG0, PG1 Gated, and Continuous Operating Modes
        4. 7.3.10.4 Warning Interrupts for System Level Diagnostics
          1. 7.3.10.4.1 Output Power Limit
          2. 7.3.10.4.2 Thermal Warning
        5. 7.3.10.5 Protections Causing Converter Disable
          1. 7.3.10.5.1 Short-Circuit and Overload Protection
          2. 7.3.10.5.2 Overvoltage Protection
          3. 7.3.10.5.3 Thermal Shutdown
        6. 7.3.10.6 Protections Causing Device Power Down
          1. 7.3.10.6.1 Undervoltage Lockout
      11. 7.3.11 OTP Error Correction
      12. 7.3.12 Operation of GPO Signals
      13. 7.3.13 Digital Signal Filtering
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Interface
        1. 7.5.1.1 Data Validity
        2. 7.5.1.2 Start and Stop Conditions
        3. 7.5.1.3 Transferring Data
        4. 7.5.1.4 I2C-Compatible Chip Address
        5. 7.5.1.5 Auto Increment Feature
    6. 7.6 Register Maps
      1. 7.6.1 Register Descriptions
        1. 7.6.1.1 LP8770_map Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Application Components
          1. 8.2.2.1.1 Inductor Selection
          2. 8.2.2.1.2 Buck Input Capacitor Selection
          3. 8.2.2.1.3 Buck Output Capacitor Selection
          4. 8.2.2.1.4 Boost Input Capacitor Selection
          5. 8.2.2.1.5 Boost Output Capacitor Selection
          6. 8.2.2.1.6 Supply Filtering Components
      3. 8.2.3 Current Limit vs Maximum Output Current
      4. 8.2.4 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.1 Overview

The LP87702 is a high-efficiency, high-performance power supply IC with two step-down DC/DC converters (Buck0 and Buck1) and boost converter for automotive and industrial applications. The input voltage range is from 2.8 V to 5.5 V. The typical application input voltage levels are 3.3 V and 5 V. VANAOVP is set to 4.3 V (typical) with 3.3 V input and boost enabled. The boost can be used as a load switch and VANAOVP is set to 5.8 V (typical) when input voltage is 5 V. VANAOVP is selected in OTP by VANA_OVP_SEL and is a fixed factory setting. Table 7-1 lists the output characteristics of the various converters.

Table 7-1 Supply Specification
SUPPLYOUTPUT
VOUT RANGE (V)RESOLUTION (mV)IMAX MAXIMUM OUTPUT CURRENT (mA)
Boost4.9 to 5.2100600
Buck00.7 to 3.3610 (0.7 V to 0.73 V)
5 (0.73 V to 1.4 V)
20 (1.4 V to 3.36 V)		3500
Buck10.7 to 3.3610 (0.7 V to 0.73 V)
5 (0.73 V to 1.4 V)
20 (1.4 V to 3.36 V)		3500

The LP87702 converters support switching clock synchronization to an external clock connected to CLKIN input. The external clock can be from 1 MHz to 24 MHz with 1-MHz steps. Alternatively, optional spread spectrum mode can be enabled to reduce EMI.

LP87702 features include diagnostics, monitoring, and protections for the devices internal and system level operation, which are the following:

  • Soft start
  • Input undervoltage lockout
  • Programmable undervoltage or window (overvoltage and undervoltage) monitoring for the input (from VANA pin)
  • Programmable undervoltage or window (overvoltage and undervoltage) monitoring for the buck and boost converter outputs
  • Two inputs (VMONx) with programmable undervoltage or window (overvoltage and undervoltage) thresholds, for monitoring external rails in the system
  • One dedicated power-good output (PG0) to which selected monitoring signals can be combined
  • Second programmable power-good output (PG1), multiplexed with general purpose output (GPO1)
  • Power good flags with maskable interrupt
  • Programmable window watchdog
  • Buck and boost converter overload detection
  • Thermal warning with two selectable thresholds
  • Thermal shutdown

LP87702 control interface:

  • Up to three enable inputs ( EN1, EN2, and EN3) with programmable power-up or power-down sequence control
  • Optional I2C (multiplexed with EN2 and EN3 inputs)
  • Interrupt signal (nINT) to host
  • Reset input (NRST)
  • One dedicated general purpose output (GPO0)
  • Watchdog disable WD_DIS, multiplexed with CLKIN/GPO2